Redis player count for clustering

main.go

@@ -1,11 +1,15 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"net"
+	"os"
+	"strconv"
 	"time"
 
+	"github.com/go-redis/redis/v9"
 	"github.com/hashicorp/consul/api"
 	"go.minekube.com/brigodier"
 	. "go.minekube.com/common/minecraft/component"
@@ -53,7 +57,7 @@ func (p *FenceProxy) init() error {
 func (p *FenceProxy) registerServers() {
 	// Get a new client
 	config := api.DefaultConfig()
-	config.Address = "consul1.pawott.de:8500"
+	config.Address = getEnv("CONSUL_ADDR", "127.0.0.1:8500")
 	client, err := api.NewClient(config)
 	if err != nil {
 		panic(err)
@@ -164,11 +168,28 @@ func (p *FenceProxy) registerCommands() {
 	))
 }
 
+var ctx = context.Background()
+var localPlayers int64 = 0
+
 // Register event subscribers
 func (p *FenceProxy) registerSubscribers() error {
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     getEnv("REDIS_ADDR", "localhost:6379"),
+		Password: "", // no password set
+		DB:       0,  // use default DB
+	})
+
 	p.Event().Subscribe(&proxy.PingEvent{}, 0, func(ev event.Event) {
 		e := ev.(*proxy.PingEvent)
 		p := e.Ping()
+		val, err := rdb.Get(ctx, "players").Result()
+		if err == redis.Nil {
+			// does not exist yet
+			rdb.Set(ctx, "players", 0, 0)
+		} else if err != nil {
+			panic(err)
+		}
+		p.Players.Online, _ = strconv.Atoi(val)
 		p.Players.Max = p.Players.Online + 1
 	})
 	p.Event().Subscribe(&proxy.LoginEvent{}, 0, func(ev event.Event) {
@@ -178,16 +199,25 @@ func (p *FenceProxy) registerSubscribers() error {
 	p.Event().Subscribe(&proxy.PlayerChooseInitialServerEvent{}, 0, func(ev event.Event) {
 		e := ev.(*proxy.PlayerChooseInitialServerEvent)
 		e.SetInitialServer(p.Servers()[0])
+		localPlayers += 1
+		rdb.Incr(ctx, "players")
+	})
+
+	p.Event().Subscribe(&proxy.DisconnectEvent{}, 0, func(ev event.Event) {
+		localPlayers -= 1
+		rdb.Decr(ctx, "players")
+	})
+
+	p.Event().Subscribe(&proxy.ShutdownEvent{}, 0, func(ev event.Event) {
+		rdb.DecrBy(ctx, "players", localPlayers)
 	})
 
 	return nil
 }
 
-func contains(list []proxy.ServerInfo, b proxy.ServerInfo) bool {
-	for _, as := range list {
-		if as == b {
-			return true
-		}
+func getEnv(key, fallback string) string {
+	if value, ok := os.LookupEnv(key); ok {
+		return value
 	}
-	return false
+	return fallback
 }